There are known stamped lamellar conductor rotors without a separate commutator, so that the brushes ride directly on the conductors. These rotors have the disadvantage of wearing out quite quickly in the region engaged by the brushes. In addition, due to the relatively numerous conductors in this region, the rotor diameter much be relatively large.
There are also known stamped lamellar conductors carried on two layered rotors with separate commutator wherein the conductors, constitute extensions of the commutator bars and alternate with conductors having no commutator bars, so that the number of commutator bars represents one-half the number of conductors of a layer, and a section contains two turns. These rotors have the disadvantage that they cannot be used with machines having an even number of pole pairs and, because of the relatively large number of commutator bars, it is necessary to make the disk relatively large in diameter.